Total Motorcycle Community Forums

I'm thinking about swapping my stock integrated reservoir and master cylinder to a remote mounted reservoir system. I need the room on the bars and to rotate the lever without tilting the reservoir all wacky.

The current size on there is an 11mm piston. Most of the parts I can find easy and rather inexpensive are larger sizes (1/2", 5/8", 14mm).

Will jumping up to a larger size change the effectiveness and safety of the brakes? Or will it just change the feel of the lever?

A smaller M/C piston will apply more pressure to the caliper pistons... more braking force, with the same amount of force applied to the brake lever. But it will move less fluid with each stroke, so the lever will have to move farther to push enough fluid into the calipers to move those pistons the same distance as before. Unless the change in M/C piston size is significant, the difference in brake lever travel will be quite small.

The opposite is true if the M/C piston is large diameter than stock. Less pressure applied to the caliper pistons and less brake lever travel required to move the same amount of fluid as before.

Try to keep the size change as small as possible, and if you can, go slightly smaller rather than bigger. That's what I would do, anyways, more braking force is better than less lever travel to me. Your opinion may be different...

Buzz, that's a good explanation. Though if I swap, it looks like bigger is the only way to go. I'm looking at a printout of all Hondas stock cylinders for each model bike and it isn't promisng. The MCs that are 11mm are are the integrated style that I'm trying to get rid of. I'll keep looking.


I'm also considering a radial style MC. They are very pricey though
The smallest I've seen those is 13mm. I don't mind the race style only (with the brake light switch) as I'm switching to the banjo bolt switch. The less things dangling off the perch the better. I need it as slim as possible so I can fit the clutch underneath.


Ok...thinking outloud....rough numbers on available MCs

11mm = .43"
12.7mm = .5 = 1/2"
13mm = .51"
14mm = .55"
15.8mm = 5/8"

The other variable in the brake question is caliper pist diameter. Here things work opposite to the M/C. Bigger caliper pistons apply more force to the rotor for the same amount of input(from the M/C) pressure. The fact that the force multiplies exponentially means that a smaller change in caliper piston size gives greater change of effect. So changeing the M/C piston diameter will create a smaller change in braking feel and power than changeing the caliper piston will. A couple of millimeters difference should not be too big a problem.